Mr Trump met with parents, teachers and students affected by school shootings on Wednesday (local time) to discuss possible responses.

While several parents wanted action on gun control, Mr Trump endorsed concealed carry for school officials.

"If you had a teacher who is adept at firearms it could very well end the attack very quickly," Mr Trump said.

One of the victims at Marjory Stoneman Douglas High School was football coach Aaron Feis, who was also employed as a security guard. He was shot and killed after jumping in front of teenagers to protect them.

"If he had a firearm he wouldn't have had to run, he would have shot and that would have been the end of it," Mr Trump commented

Mr Trump argued for sending veterans into schools to stop shooters.

You can't have "100 security guards," he said. However you could give "a lot of people" guns - and "they may be marines".

Mr Trump also called for more mental institutions to hold people.

"Today if you catch somebody they don't know what to do with them... there's no mental institution, there's no place to bring 'em," the Toronto Star reported him saying.

Gun owners are a key part of Mr Trump's base, and he embraced gun rights on his campaign.

Nonetheless he has indicated in recent days that he was willing to consider ideas not in keeping with National Rifle Association orthodoxy, included age restrictions for buying assault-type weapons.